Extended catalyst life Fischer-Tropsch process

Abstract

A process for extending the life of a Fisher-Tropsch catalyst in a process for converting synthesis gas produced in an autothermal reactor by the substoichiometric oxidation of a light hydrocarbon gas by removing ammonia from the synthesis gas prior to passing the synthesis gas to a Fischer-Tropsch reactor.

We claim:  
     
       1. An extended catalyst life process for producing liquid hydrocarbons from a synthesis gas, the process comprising: 
       a) producing a synthesis gas comprising hydrogen and carbon monoxide by substoichiometric oxidation of a light hydrocarbon with an oxygen-containing stream comprising air or oxygen-enriched air;  
       b) adjusting the hydrogen to carbon monoxide ratio in the synthesis gas to a range from about 1.0 to about 5.0;  
       c) cooling the synthesis gas to a temperature below about 150° F.;  
       d) separating water from the synthesis gas;  
       e) reducing the ammonia content of the synthesis gas to a value below about 10 ppmv by contacting the synthesis gas with an aqueous stream containing an acidic component; and  
       f) reacting at least a portion of the reduced ammonia content synthesis gas in the presence of a catalyst comprising cobalt, ruthenium, or cobalt and ruthenium supported on an inorganic metal oxide support and a liquid comprising reaction product hydrocarbon liquids to produce liquid hydrocarbons.  
     
     
       2. The process of claim  1  wherein the synthesis gas is produced in an autothermal reactor. 
     
     
       3. The process of claim  1  wherein the ammonia content is reduced to a value below about 5 ppmv. 
     
     
       4. The process of claim  1  wherein the ammonia content is reduced to a value below about 1 ppmv. 
     
     
       5. The process of claim  1  wherein the hydrogen to carbon monoxide ratio is from about 1.5 to about 3.0. 
     
     
       6. The process of claim  1  wherein the synthesis gas is reacted in a slurry bubble column reactor containing a finely divided catalyst comprising cobalt, ruthenium, or cobalt and ruthenium supported on a metal oxide selected from oxides of Groups IIIA, IIIB, IVB, VB, VIB and VIIIB metal oxides, silica, silica-alumina and mixtures thereof. 
     
     
       7. The process of claim  6  wherein the catalyst comprises cobalt supported on alumina, silica, or titania and combinations thereof. 
     
     
       8. The process of claim  7  wherein the catalyst comprises cobalt supported on alumina. 
     
     
       9. The process of claim  1  wherein the catalyst further comprises a promoter. 
     
     
       10. The process of claim  1  wherein the promoter is selected from the group consisting of zirconium, titanium, rhenium, cerium, hafnium, uranium, ruthenium and combinations thereof. 
     
     
       11. The process of claim  1  wherein the acidic component is formed by adding carbon dioxide to the aqueous stream.